Add SwiftLint to build script

[AJ9]

As discussed in #79 and here, adding SwiftLint as a build script will reduce regression SwiftLint errors. This build script does check the entire SwiftGen project and I've added the following exclusions (to the .swiftlint.yml file) with the following reasons:

disabled_rules: 
  - force_try
  - force_cast 
  - variable_name 

• force_try - Used in some unit tests to create result objects
• force_cast - Used here and here
• variable_name - Used sensibly here

[AJ9]

This does result in 242 issues, maybe we can find a way of just checking the expected folder?

[AliSoftware]

great work thx!
I think we might get rid of the try! calls by replacing them with guard try? … else { fatalError("some explicit message") } instead, which would both satisfy SwiftLint and make better error messages, as I hate killing ponies 😉

[AliSoftware]

This does result in 242 issues, maybe we can find a way of just checking the expected folder?

You can use swiftlint lint --path …/expected for that.

The main concern is indeed to ensure the code generated by SwiftGen match SwiftLint styling rules, so the expected folder is indeed the most important one to check. But it would be cool to make the codebase of SwiftGen itself cleaner by addressing those 242 warnings too.

I think we could use swiftlint lint --strict --path …/path/to/expected in the .travis.yml file, so that Continuous Integration only check the expected folder, and fail even on warning (--strict) to prevent new templates to introduce bad style.

Then we could use the simple swiftlint command (without --strict nor --path) in the Script Build Phase to check the whole codebase (and not just expected), and only warn (not fail); then (later?) address those lint warnings in the SwiftGen codebase itself.

[AliSoftware]

I just realized a problem: swiftlint won't be able to lint the files in UnitTests/expected because those files have the .swift.out extension, not just .swift, so they are discarded by SwiftLint and not analyzed. SwiftLint only analyze files having the .swift extension.

So I'm not sure there is a proper way to validate that the templates or their output does not violate SwiftLint rules. Maybe there is hope with the swiftlint lint --use-stdin somehow, but not with swiftlint directly analyzing the files.

[AliSoftware]

Hi @AJ9

I finally took the time to merge this. In fact I reintegrated SwiftLint the way you started to do it (but in my own branch to start anew since your branch started to be a bit behind the latest merged PRs), and in addition I added linting for both the templates and the SwiftGen code itself, and fixed all the warnings & errors generated by the listing.

Thanks again for taking a stab at it!